The invention relates to wireless communication systems within the art of transmitting a signal from an emitter to a receiver. These systems include infrared (xe2x80x9cIRxe2x80x9d) communication systems and radio frequency (xe2x80x9cRFxe2x80x9d) communication systems as well as other types.
Systems including stationary microphones may be used for transforming a sound signal to an electrical signal, which is modulated, using modulating electronics, for IR transmission. The modulating electronics may be connected to a stationary IR emitter, which transmits the modulated signal. An IR receiver, mounted for example in a headset or a body-pack, may be provided to listeners who are located in a relevant environment and who desire to receive the emitted signal. The received signal is demodulated in demodulating electronics and transferred to earphones worn by the listener. The receivers and demodulating electronics may be connected to various other types of transmission equipment, such as loudspeakers, via external amplification systems.
Such stationary systems will only function in a satisfactory manner in a situation where the speaker is in a stationary position, such as a conference situation, where the speaker usually stands behind a podium speaking directly to an audience before him. However, a number of situations may arise where the stationary system is insufficient, due to the speaker""s need to move into different positions, such as in the educational environment of schools, universities and the like. A teacher in a classroom may need to walk back and forth among the students, write on a blackboard facing away from the students, and move his head from side to side to capture the attention of the student audience on all sides. An actor on a stage may present another example of a situation where the stationary microphone/emitter units fail to be adequate.
Handheld microphone/emitter units exist but are not convenient for a speaker using them. The speaker is unable to use both hands and at the same time hold the microphone in a correct position. This is inconvenient in many situations, namely for a speaker in an educational environment who wishes to write on the board with one hand and hold a book with the other.
Headsets that are mounted on the head of the speaker and include a microphone that is mounted on a boom, again, solve some but not all of the problems associated with stationary systems. These headsets are undesirable as many find that the head mounting interferes with their hair and is generally uncomfortable.
Clip-on type microphones solve some but not all of the problems of the stationary microphone/emitter systems. These type of microphones pick up background noise and are prone to acoustic feedback. Moreover, in a classroom environment, the speaker usually moves and rotates his head from side to side. Some movements and rotation of the speaker""s head from side to side often weakens the sound pressure conveyed to the microphone, resulting in a weak signal that is poorly intelligible for the listeners.
Another available microphone system is the Collar(trademark) microphone from Anchor. This system uses only one microphone. One of the problems with the Collar(trademark) microphone is the variation in input sound pressure level when the user rotates his/her head from side to side causing a varying output to the listener.
Due to the above-mentioned disadvantages, the educational environments have only been able to use RF transmission systems. However, because the RF signal may travel beyond the intended classroom, these systems require a different transmission frequency to be used for each classroom. As a result, such systems may have limitations of use where the required number of frequencies cannot be provided. Further, in such systems, the transmitter and receivers have to be tuned to the same frequency, which may be cumbersome when a significant number of different frequencies are used.
Compared to the RF transmission systems, the IR transmission systems have the advantage of not being able to transmit a signal beyond the physical limitations of the environment, i.e., the walls, the floor and the ceiling of a classroom. As a result, the same transmission frequency may be used in adjacent classrooms in a school.
IR transmission and communications systems, on the other hand, have their own disadvantages. In order to remedy the disadvantages of stationary IR transmission systems, systems that include portable IR emitters and portable microphones may be used. The emitter transmits a signal, which is received by a stationary receiver. The signal is then processed and transmitted to stationary loudspeakers. The portable microphone and emitter normally are arranged as neckbands or clip-on units that are placed in front of the body of the user. Movements of the speaker""s head may cause an insufficient input to the microphone due to variations in sound pressure levels and result in a similarly insufficient output. Additionally, this type of mounting may cause the body of the speaker to fall between the emitter and the receiver, thereby possibly blocking the IR signal emitted by the emitter from reaching the receiver. Due to these disadvantages and the like, the IR communication systems have been usually deemed deficient when used for non-stationary speakers.
It is an object of the present invention to provide a wireless communication system and/or a microphone system for use in connection with a wireless communication system, which allow the speaker to move his/her head from side to side without influencing the microphone input signal significantly. It is a further object to provide a microphone system or a wireless communication system having a microphone system, which does not interfere with the hair of the speaker and which allows the speaker to have both hands free for other uses while utilizing the system for speaking.
According to the embodiments of the invention disclosed in this specification, the above objectives may be achieved by a system including: at least two microphones for receiving a user""s voice; modulation electronics in connection with the microphones for modulating the microphone signal; at least one signal emitter in connection with the modulation electronics adapted for transmitting a modulated microphone signal; a stationary part including at least one receiver for receiving the transmitted modulated microphone signal; and demodulating electronics in connection with the at least one receiver. The system further includes end transmission equipment, in which the at least two microphones form part of a single portable unit suitable for placement around the user""s neck, wherein the unit includes a flexible wearing element having a free end, wherein the at least two microphones are placed in a fixed position in relation to the flexible wearing element, with an angle between the main direction of at least two microphones in the range of 30-180 degrees. The angle in various embodiments may range between 30-80 degrees, may be set at 60-120 degrees, or may be approximately 90 degrees.